Double-walled vacuum container



May 14, 1935.- A. H, PAYsoN DOUBLE WALLED VACUUM CONTAINER Filed May 5,1954 ...zizuuslssuuvuun INVENTOR /PTHL/l? H. PAYSO/V I ATTORN EYPatentedk May `14, 1935 :lip-:1'

2,`oo1,1f54f o p `DOUBLE-WALIJED.SVAUUUll/I CONTAINERllrtlinlVHfPayson",` YConn.`.assignor to The American Thermos BottleCompany, Norwich, Conn`.`,wa corporation of fOhio' Appliiation` Maya1934, serial Nb. 724.1963; [3f crains. loller- 681m My invention relatestodouble-,Walled vacuum containers of glass, and its object is toprovide a container of that type in which the silvered walls of thevacuum space have a clear strip like 51a window for observing thecontents of the container. This window is produced by inserting asuitable member into the vacuum space and holding it in rm contact withopposite portions of the walls while these are being treated with asilvering solution. When the silveringoperation is finished, theglassareas covered by the inserted member remain unsilvered andtransparent to serve as a sight opening.

`In practice I have obtained satisfactory results .I l5 by means of aflexible rubber tube, which is easily inserted into the vacuum space ofthe container through the usual evacuating tubulation. Ihe inserted tubeis then inflated and thereby forced into rrn contact with opposite areasof the walls, and these areas are not reached by the silvering solution,but remain clear glass. The tube is thereupon deated and withdrawn.

The novel features and practical advantages of `Iny invention will beunderstood from a description of the accompanying drawing, in which Fig.1 is `a vertical section of a double-walled glass container with arubber tube inserted into the Vacuum space prior to the silvering oper-30 ation;

Fig. 2 is a front view of Fig. 1,` showing the vertical window formed inthe container by use of the rubber tube; 1

Fig. 3 shows a modification in which thel inserted tube is looped at itsinner end to cover a circulararea which shall remain unsilvered; and jFig. 4 shows a double-walled container having a; sight opening formed bythe looped tube of 40 Fig. 3.` p

, In all the views there is a double-walled cylindrical container ofglass, comprising an outer wall Il] and an inner Wall I2 integrallyunited and separated by a space I3, which in the finished jar isevacuated to provide heat-insulation for the contents.v `The inside wallsurface of the vacuum space I3 is silvered to improve the heatinsulatingpropertiesof the container, and this silvering is usually done bypouring a silvering 5 `solution through the open tubulaton I4, andagitating the jar or bottle until a `coating of silver is precipitateduniformly on the walls of `thevacuurn space. The excess solution is thenpoured oi, the silvered chamber is rinsed with clear water, and nallythe container is put through the usual baking and exhaustingoperations-.1., i I I Insome instancesit has been found neces.- sary toobserve thecontents `of the silvered container from the outside,`and tomake that pos- 5 sible I form a window or sight opening lengthwise ofthe container by blocking off opposing portions of the vacuum wallsduring the silvering operation. One way of doing this is shown in Fig.1, where a straight soft rubber tube I5 is 10 inserted through thetubulation I4, and is then inflated to force it into firm contact Withthe walls of the vacuum space I3.` The inflated tube may be tied with apiece of string I6 at its outer end or held closed in any otherpractical way. The silvering solution is then poured into space I3through tubulation I or through another hole in the outer wall Ill. 'Ihecontainer is then rolled or otherwise agitated to bring the solutioninto contact with the entire wall surface of the vacuum space I3, exceptwhere the inated tube I5 covers the glass. When the silvering operationis finished and the deflated tube withdrawn, there is left an unsilveredtrans'- parent strip I'I through which the contents I 8 25 of the jarmay be observed.

In Fig. 3, the inserted rubber tube I5 is doubled and is tied at I 9 (anelastic band will do) to form a` loop 2U, which covers a circular areaon each wall of the vacuum space. Consequently, when the looped tube I5is withdrawn after the silvering operation (the tube being deflated forthat purpose), the window 2| formed in the silvered walls has adisk-shaped'enlargement 22 at v the top. Manifestly, other forms ofwindow may be produced by varying the shape of the inserted member toblock 01T such portions of the glass as may be required in anyparticular-case.

I want it understood that my invention is not limited to the details setforth, for changes vand 40 modifications may be made Within the scope ofthe appended claims. Throughout the descripf tion and claims I use theterm vacuum space to designate the space between the twowalls of thenested glass cylinders, irrespective of whether a vacuum is actuallydrawn therein or not. In some double-walled bottles and jars this spaceis `sealed off at ,atmospheric pressure, or it may be lled with carbondioxide gas or other medium having heat-insulating properties. All Suchdouble-walled containers have a vacuum space Within the broad meaning ofthe term as used in the claims. Further, when I speakv of the silveredwalls of the vacuum space, I do not necessarily mean a coating ofsilver, but I include PJrArENrIQFFICE any silver-like or mirror-likecoating, such as, for example, nickel, magnesium, copper, and so forth.

I claim as my invention:

1. In the manufacture of double-walled vacuum containers, the method offorming an unsilvered window in the silvered inner walls of the vacuumspace, which method comprises inserting a member into said space andmaintaining it in rm contact with opposing portions of said walls alonga sufficiently wide area substantially lengthwise of the container, andtreating said inner walls with a silvering solution while Said member sheld in place, whereby the opposing wall surfaces covered by said memberremain unsilvered and transparent to serve as a window or sight opening,the inserted member being then withdrawn.

2. In the manufacture of double-walled vacuum containers, the method offorming an unsilvered window in the silvered inner walls of the vacuumspace, which method comprises inserting an expansible elastic memberinto said space and forcing it into rm contact with opposing portions ofSaid walls along a sufficiently wide area substantially lengthwise ofthe container, and treating said inner walls with a silvering solutionwhile the expanded member remains in Contact with said walls, wherebythe opposing wall surfaces covered by said member remain unsilvered andtransparent to serve as a window or sight opening, the inserted memberbeing then withdrawn.

3. In the manufacture of double-walled vacuum containers, the method offorming an unsilvered window in the silvered inner walls of the vacuumspace, which method comprises inserting an infiatable rubber tube intosaid space, inflating the inserted tube to force it into firm contactwith opposing portions of said walls along a suiciently wide areasubstantially lengthwise of the container, and treating said inner wallswith a silvering solution while the inflated tube remains in position,whereby the opposing wall surfaces covered by the inflated tube remainunsilvered and transparent to serve as a window or sight opening, theinserted tube being then deflated and Withdrawn.

ARTHUR H. PAYSON.

